Reasons to amend soil:
Amending garden soil by adding organic matter improves moisture permeability and retention. This will keep the soil both from drying too quickly and staying wet too long. It also improves the nutrient-holding capacity of the soil and allows oxygen to move easily down to the roots. In addition, soil amendment aids biological activity; bacteria, worms, and insects thrive in a soil that is rich in organic matter.
How to amend soil:
Add kitchen compost (avoid animal products), yard waste, composted manure, straw, grass, etc. Peat moss can also be used. Leaves and grass clippings can be worked into the soil directly and will decompose slowly, however if they are composted beforehand they will be available as nutrition faster.
A new garden will benefit from a 50% ration of soil to compost. Add about three to six inches of compost material on top of the garden. Till it in to the soil to a depth of about one foot.
How to determine what kind of soil you have:
Clay – Feels sticky. Clay soil is very dense and will readily retain its shape when pressed into a ball. If the soil does not fall apart after being shaped in your hand, then you probably have clay-based soil. This type of soil is not healthy for plants because oxygen and nutrients cannot easily penetrate the soil down to the roots. The plants essentially are smothered.
Sand – Feels gritty. Sandy soil will not hold its shape at all when pressed in your hand. It will simply sift between your fingers much like the sand in an hourglass. The problem with sandy soil is that nutrients are easily washed away and are not available as plants need them. In additiion, the soil dries very quickly so plants easily suffer from dehydration. Addiing lots of compost will help with nutrient and moisture retention.
Silt – Feels smooth and silky. Silt soil makes is very good on farms, but, makes mud when wet, and erodes easily. In dry weather it can simply blow away therefore amending a silt soil will help keep the soil in place and improve oxygen flow to the roots of plants.
A well-amended soil will retain its shape momentarily because of the moisture content, but it should crumble easily when you rub it in between your fingers.